Impact of INDOEX data in the NCMRWF analysis-forecast system and evolution of boundary layer structure during IFP-99

The observing process is the most important and expensive component of the forecasting system. Impact studies are means of assessing the value of observing systems in terms of the benefit they deliver to model forecasts, and guide efforts to ensure cost-effective deployment of observations. In the present work, the INDOEX data from IFP-99 for the period 1-8 February 1999 (two glass-sonde observations per day) were assimilated in the global data assimilation system of NCMRWF, The impact of these observations on the analysis and subsequent forecasts was studied, Various aspects of the boundary layer parameters were studied using the first order closure scheme for PBL that include evolution of vertical profiles of various meteorological parameters, diurnal variation of fluxes, etc, The vertical profiles obtained from the model forecasts were compared with the available observations from INDOEX.